Melflufen or pomalidomide plus dexamethasone for patients with multiple myeloma refractory to lenalidomide (OCEAN): a randomised, head-to-head, open-label, phase 3 study

Multiple myeloma refractory to lenalidomide: A systematic literature review of trials and real-world evidence

The growing use of frontline lenalidomide treatment in multiple myeloma (MM) is increasing the proportion of lenalidomide-refractory patients, which may limit the efficacy of subsequent lines of treatment (LOT). This systematic literature review (January 2008-October 2023) of clinical trials (CT) and real-world studies (RW) assessed treatment outcomes in adults with relapsed/refractory MM (RRMM) who were previously treated with ≥1 LOT, progressed and were lenalidomide-refractory. Medline, EMBASE and additional electronic databases were searched for articles published in English. Primary outcomes included progression-free survival (PFS), overall survival (OS) and overall/objective response rate (ORR); 24 CT and 19 RW were included. For CT, the population-weighted mean of median PFS (CT = 14) and OS (CT = 6) were shorter in the lenalidomide-refractory cohort (months: 8.8 [n = 2699] and 21.7 [n = 1066], respectively) than the intent-to-treat population (months: 13.8 [n = 5380] and 35.9 [n = 2264], respectively); the population-weighted (N = 2142) mean ORR for lenalidomide-refractory patients (CT = 18) was 56.0%. RW reported considerable variation in PFS (RW = 7), OS (RW = 8) and ORR (RW = 8); and median PFS (RW = 2; months) was lower in lenalidomide/bortezomib-refractory (5.5/5.5; n = 81/n = 25) versus lenalidomide-refractory (7.3/8.0; n = 81/n = 61) patients. These data provide evidence that clinical trials and real-world outcomes are suboptimal in lenalidomide-refractory patients with RRMM, highlighting the need to improve treatment options for this population.

Peptides for microbe-induced cancers: latest therapeutic strategies and their advanced technologies

Cancer is a significant global health concern associated with multiple distinct factors, including microbial and viral infections. Numerous studies have elucidated the role of microorganisms, such as Helicobacter pylori (H. pylori), as well as viruses for example human papillomavirus (HPV), hepatitis B virus (HBV), and hepatitis C virus (HCV), in the development of human malignancies. Substantial attention has been focused on the treatment of these microorganism- and virus-associated cancers, with promising outcomes observed in studies employing peptide-based therapies. The current paper provides an overview of microbe- and virus-induced cancers and their underlying molecular mechanisms. We discuss an assortment of peptide-based therapies which are currently being developed, including tumor-targeting peptides and microbial/viral peptide-based vaccines. We describe the major technological advancements that have been made in the design, screening, and delivery of peptides as anticancer agents. The primary focus of the current review is to provide insight into the latest research and development in this field and to provide a realistic glimpse into the future of peptide-based therapies for microbe- and virus-induced neoplasms.

Targeted Delivery Strategies for Multiple Myeloma and Their Adverse Drug Reactions

Currently, multiple myeloma (MM) is a prevalent hematopoietic system malignancy, known for its insidious onset and unfavorable prognosis. Recently developed chemotherapy drugs for MM have exhibited promising therapeutic outcomes. Nevertheless, to overcome the shortcomings of traditional clinical drug treatment, such as off-target effects, multiple drug resistance, and systemic toxicity, targeted drug delivery systems are optimizing the conventional pharmaceuticals for precise delivery to designated sites at controlled rates, striving for maximal efficacy and safety, presenting a promising approach for MM treatment. This review will delve into the outstanding performance of antibody-drug conjugates, peptide-drug conjugates, aptamer-drug conjugates, and nanocarrier drug delivery systems in preclinical studies or clinical trials for MM and monitor their adverse reactions during treatment.

Dose Optimization of Targeted Therapies for Oncologic Indications

Therapeutic advances in oncology in the 21st century have contributed to significant declines in cancer mortality. Notably, targeted therapies comprised the largest proportion of oncology drugs approved by the United States (US) Food and Drug Administration (FDA) over the past 25 years and have become the standard of care for the treatment of many cancers. However, despite the metamorphosis of the therapeutic landscape, some aspects of cancer drug development have remained essentially unchanged. In particular, the dose-finding methodology originally developed for cytotoxic chemotherapy drugs continues to be implemented, even though this approach no longer represents the most appropriate strategy for modern cancer therapies. In recognition of the need to reconsider assumptions, adapt the dose selection process for newer drugs, and design alternative strategies, the FDA has undertaken several initiatives in recent years to address these concerns. These actions include the launch of Project Optimus in 2021 and the issuance of draft guidance for industry on dose optimization of oncology drugs in 2023. Amid this evolving regulatory environment, the present manuscript reviews case studies for six different targeted cancer therapies, highlighting how dose-finding challenges have been managed to date by oncologists, sponsors, and regulators.

Small molecule anticancer drugs approved during 2021-2022: Synthesis and clinical applications

Drugs have structural homology across similar biological targets. Small molecule drugs have the efficacy to target specific molecular targets within the cancer cells with enhanced cell membrane permeability, oral administration, selectivity, and specific affinity. The objective of this review is to highlight the clinical importance and synthetic routes of new small molecule oncology drugs approved by the FDA during the period 2021-2022. These marketed drugs are listed based on the month and year of approval in chronological order. We believed that an in-depth insight into the synthetic approaches for the construction of these chemical entities would enhance the ability to develop new drugs more efficiently.

Patient-Reported Outcomes in Phase 3 Clinical Trials for Blood Cancers: A Systematic Review

Importance

Published research suggests that patient-reported outcomes (PROs) are neither commonly collected nor reported in randomized clinical trials (RCTs) for solid tumors. Little is known about these practices in RCTs for hematological malignant neoplasms.

Objective

To evaluate the prevalence of PROs as prespecified end points in RCTs of hematological malignant neoplasms, and to assess reporting of PROs in associated trial publications.

Evidence Review

All issues of 8 journals known for publishing high-impact RCTs (NEJM, Lancet, Lancet Hematology, Lancet Oncology, Journal of Clinical Oncology, Blood, JAMA, and JAMA Oncology) between January 1, 2018, and December 13, 2022, were searched for primary publications of therapeutic phase 3 trials for adults with hematological malignant neoplasms. Studies that evaluated pretransplant conditioning regimens, graft-vs-host disease treatment, or radiotherapy as experimental treatment were excluded. Data regarding trial characteristics and PROs were extracted from manuscripts and trial protocols. Univariable analyses assessed associations between trial characteristics and PRO collection or reporting.

Findings

Ninety RCTs were eligible for analysis. PROs were an end point in 66 (73%) trials: in 1 trial (1%) as a primary end point, in 50 (56%) as a secondary end point, and in 15 (17%) as an exploratory end point. PRO data were reported in 26 of 66 primary publications (39%): outcomes were unchanged in 18 and improved in 8, with none reporting worse PROs with experimental treatment. Trials sponsored by for-profit entities were more likely to include PROs as an end point (49 of 55 [89%] vs 17 of 35 [49%]; P < .001) but were not significantly more likely to report PRO data (20 of 49 [41%] vs 6 of 17 [35%]; P = .69). Compared with trials involving lymphoma (18 of 29 [62%]) or leukemia or myelodysplastic syndrome (18 of 28 [64%]), those involving plasma cell disorders or multiple myeloma (27 of 30 [90%]) or myeloproliferative neoplasms (3 of 3 [100%]) were more likely to include PROs as an end point (P = .03). Similarly, compared with trials involving lymphoma (3 of 18 [17%]) or leukemia or myelodysplastic syndrome (5 of 18 [28%]), those involving plasma cell disorders or multiple myeloma (16 of 27 [59%]) or myeloproliferative neoplasms (2 of 3 [67%]) were more likely to report PROs in the primary publication (P = .01).

Conclusions and Relevance

In this systematic review, almost 3 of every 4 therapeutic RCTs for blood cancers collected PRO data; however, only 1 RCT included PROs as a primary end point. Moreover, most did not report resulting PRO data in the primary publication and when reported, PROs were either better or unchanged, raising concern for publication bias. This analysis suggests a critical gap in dissemination of data on the lived experiences of patients enrolled in RCTs for hematological malignant neoplasms.

PORT: A Randomized, Cross-Over, Phase 2 Study of Melflufen Peripheral Versus Central Intravenous Administration in Patients With Relapsed/Refractory Multiple Myeloma

BACKGROUND

Melflufen, a first-in-class alkylating peptide-drug conjugate, rapidly enters tumor cells and metabolizes to melphalan. In previous studies, melflufen was administered via central venous catheter (CVC). However, administration by peripheral venous catheter (PVC) may be preferable.

PATIENTS AND METHODS

PORT was a two-period, phase 2 crossover study of CVC versus PVC melflufen administration in patients with relapsed/refractory multiple myeloma. Adults with ≥ 2 prior therapies refractory to/intolerant of an immunomodulatory drug and a proteasome inhibitor were randomized 1:1 to weekly oral dexamethasone plus melflufen (40 mg) via CVC or PVC infusion on day 1 of 28-day cycle 1. In cycle 2, patients continued dexamethasone and crossed over to the other melflufen administration route. In cycle 3, all patients received melflufen until progression; PVC or CVC routes were allowed based upon investigator decision. Pharmacokinetic sampling was performed during and after melflufen infusion. Primary endpoints were melphalan pharmacokinetic parameters (Cmax, AUC(0-t), and AUC(0-∞)) and frequency and severity of PVC-related local reactions.

RESULTS

The 90% CIs for adjusted geometric mean ratios for pharmacokinetic parameters following CVC versus PVC administration were within the 0.8-1.25 bioequivalence range (Cmax 0.946 [90% CI: 0.849, 1.053]; AUC(0-t) 0.952 [90% CI: 0.861, 1.053]; AUC(0-∞) 0.955 [90% CI: 0.863, 1.058]). In both arms, adverse events were primarily hematological and similar; no phlebitis or local infusion-related reactions occurred.

CONCLUSION

Melflufen PVC and CVC administrations are bioequivalent based on melphalan pharmacokinetic parameters. Melflufen via PVC was well tolerated, with no infusion-related reactions or new safety signals and may represent an alternative route of administration.

An open-label phase 2 study treating patients with first or second relapse of multiple myeloma with carfilzomib, pomalidomide, and dexamethasone (KPd): SELECT study

Once-weekly carfilzomib at 56 mg/m2 plus immunomodulatory drugs and dexamethasone has shown efficacy and tolerability treating early relapsed/refractory multiple myeloma (RRMM). The phase 2 SELECT study (NCT04191616) evaluated efficacy/safety of weekly carfilzomib, pomalidomide, and dexamethasone (KPd) in early RRMM patients refractory to lenalidomide. All 52 treated patients were refractory to prior treatment, and 19 (37%) were triple-class refractory. Overall response rate (ORR; primary endpoint) was 58% (35% ≥ very good partial response, 6% ≥ complete response); median response duration was 20.3 months. Minimal residual disease negativity (10-5) was achieved in 10% of patients. Median progression-free survival was 11.1 months; median overall survival was 18.8 months. Adverse events (AEs) were consistent with the known safety profile including grade ≥3 treatment-emergent AEs reported in 67% of patients. Although the primary endpoint of ORR was not met, KPd showed meaningful clinical benefits in lenalidomide-refractory RRMM patients, including those who were daratumumab-refractory and/or triple-class refractory.

Time-to-Event Endpoints in Imaging Biomarker Studies

Time-to-event endpoints are widely used as measures of patients' well-being and indicators of prognosis. In imaging-based biomarker studies, there are increasingly more studies that focus on examining imaging biomarkers' prognostic or predictive utilities on those endpoints, whether in a trial or an observational study setting. In this educational review article, we briefly introduce some basic concepts of time-to-event endpoints and point out potential pitfalls in the context of imaging biomarker research in hope of improving radiologists' understanding of related subjects. Besides, we have included some review and discussions on the benefits of using time-to-event endpoints and considerations on selecting overall survival or progression-free survival for primary analysis. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Melflufen in relapsed/refractory multiple myeloma refractory to prior alkylators: A subgroup analysis from the OCEAN study

Melphalan flufenamide (melflufen), a first-in-class alkylating peptide-drug conjugate, plus dexamethasone demonstrated superior progression-free survival (PFS), but not overall survival (OS), versus pomalidomide plus dexamethasone in relapsed/refractory multiple myeloma in the OCEAN study. Time to progression (TTP) <36 months after a prior autologous stem cell transplantation (ASCT) was a negative prognostic factor for OS with melflufen. This post hoc exploratory analysis evaluated patients refractory to prior alkylators (e.g., cyclophosphamide and melphalan) in OCEAN. In 153 patients refractory to prior alkylators (melflufen, n = 78; pomalidomide, n = 75), the melflufen and pomalidomide arms had similar median PFS (5.6 months [95% CI, 4.2-8.3] vs. 4.7 months [95% CI, 3.1-7.3]; hazard ratio [HR], 0.92 [95% CI, 0.63-1.33]) and OS (23.4 months [95% CI, 14.4-31.7] vs. 20.0 months [95% CI, 12.0-28.7]; HR, 0.92 [95% CI, 0.62-1.38]). Among alkylator-refractory patients with a TTP ≥ 36 months after a prior ASCT or no prior ASCT (melflufen, n = 54; pomalidomide, n = 53), the observed median PFS and OS were longer in the melflufen arm than the pomalidomide arm. The safety profile of melflufen was consistent with previous reports. These results suggest that melflufen is safe and effective in patients with alkylator-refractory disease, suggesting differentiated activity from other alkylators.

Histone deacetylase-based dual targeted inhibition in multiple myeloma

Despite enormous advances in terms of therapeutic strategies, multiple myeloma (MM) still remains an incurable disease with MM patients often becoming resistant to standard treatments. To date, multiple combined and targeted therapies have proven to be more beneficial compared to monotherapy approaches, leading to a decrease in drug resistance and an improvement in median overall survival in patients. Moreover, recent breakthroughs highlighted the relevant role of histone deacetylases (HDACs) in cancer treatment, including MM. Thus, the simultaneous use of HDAC inhibitors with other conventional regimens, such as proteasome inhibitors, is of interest in the field. In this review, we provide a general overview of HDAC-based combination treatments in MM, through a critical presentation of publications from the past few decades related to in vitro and in vivo studies, as well as clinical trials. Furthermore, we discuss the recent introduction of dual-inhibitor entities that could have the same beneficial effects as drug combinations with the advantage of having two or more pharmacophores in one molecular structure. These findings could represent a starting-point for both reducing therapeutic doses and lowering the risk of developing drug resistance.

Interpretations of the Role of Plasma Albumin in Prognostic Indices: A Literature Review

This review assesses how publications interpret factors that influence the serum or plasma albumin (PA) level in prognostic indices, focusing on inflammation and nutrition. On PubMed, a search for "albumin AND prognosis" yielded 23,919 results. From these records, prognostic indices were retrieved, and their names were used as search strings on PubMed. Indices found in 10 or more original research articles were included. The same search strings, restricted to "Review" or "Systematic review", retrieved yielded on the indices. The data comprised the 10 latest original research articles and up to 10 of the latest reviews. Thirty indices had 294 original research articles (6 covering two indices) and 131 reviews, most of which were from recent years. A total of 106 articles related the PA level to inflammation, and 136 related the PA level to nutrition. For the reviews, the equivalent numbers were 54 and 65. In conclusion, more publications mention the PA level as a marker of nutrition rather than inflammation. This is in contrast to several general reviews on albumin and nutritional guidelines, which state that the PA level is a marker of inflammation but not nutrition. Hypoalbuminemia should prompt clinicians to focus on the inflammatory aspects in their patients.

Benefit Versus Risk Assessment of Melflufen and Dexamethasone in Relapsed/Refractory Multiple Myeloma: Analyses From Longer Follow-up of the OCEAN and HORIZON Studies

INTRODUCTION

Melphalan flufenamide (melflufen), a first-in-class alkylating peptide-drug conjugate, plus dexamethasone demonstrated superior progression-free survival (PFS) but directionally different overall survival (OS) favoring pomalidomide (hazard ratio [HR], 1.10) in OCEAN.

METHODS

These analyses further investigated prognostic subgroups impacting survival in updated data from the randomized, phase 3 OCEAN study (NCT03151811; date: February 3, 2022) and the phase 2 HORIZON study (NCT02963493; date: February 2, 2022).

RESULTS

In OCEAN, subgroups prognostic for OS were age (P = .011; <65 years favored pomalidomide) and no previous autologous stem cell transplant (ASCT) or progression >36 months after ASCT (P = .001; favored melflufen). Overall, 245 of 495 (49%) patients randomized had received a previous ASCT, of which 202 (82%) had progressed within 36 months following their ASCT. When excluding patients who had progressed <36 months post-ASCT (melflufen group, n = 145; pomalidomide group, n = 148), median OS was 23.6 months with melflufen and 19.8 months with pomalidomide (HR, 0.83 [95% CI, 0.62-1.12]; P = .22). Among patients with triple-class refractory disease in HORIZON, patients who had progressed <36 months post-ASCT (n = 58) had a lower response rate and shorter duration of response and PFS than the remaining patients (n = 52). Safety was consistent with previous reports.

CONCLUSION

These analyses demonstrate a consistent benefit for melflufen and dexamethasone in patients with relapsed/refractory multiple myeloma who have not received an ASCT or progressed >36 months after receiving an ASCT (ClinicalTrials.gov identifier: NCT03151811).

A safety review of recently approved and emerging drugs for patients with relapsed or refractory multiple myeloma

INTRODUCTION

Multiple new drugs have been approved over the past 5 years for the treatment of relapsed/refractory multiple myeloma (RRMM), and these are being increasingly widely used. Clinicians need to familiarize themselves with common toxicities associated with these drugs and with novel toxicities requiring specific management and supportive care.

AREAS COVERED

We review common toxicities associated with agents approved for RRMM in the past 5 years, including the anti-CD38 monoclonal antibody isatuximab, the antibody-drug conjugate belantamab mafodotin, the bispecific antibody teclistamab, the chimeric antigen receptor (CAR) T cell products idecabtagene vicleucel and ciltacabtagene autoleucel, the selective inhibitor of nuclear export compound selinexor, and the drug-peptide conjugate melflufen, as well as toxicities associated with emerging agents for RRMM including additional bispecific antibodies, the BCL-2 inhibitor venetoclax, and the cereblon E3 ligase modulators iberdomide and mezigdomide. We searched the published literature using PubMed, plus congress abstracts, for the above list of drug names or classes and 'myeloma.'

EXPERT OPINION

Optimal management of toxicities associated with these recently approved and emerging therapies will be critical in maximizing clinical benefit and aiding widespread adoption in routine clinical practice. We summarize current recommendations and guidelines and provide expert insights into supportive care requirements.

Randomised controlled trials evaluating anticancer therapies in haematological cancers: an overview of global research activity

Background

Design, results, and interpretation of oncology randomised controlled trials (RCTs) have changed substantially over the past decade. In this study, we describe all RCTs evaluating anticancer therapies in haematological cancers published globally during 2014-2017 with comparisons with solid tumours RCTs.

Methods

A PubMed literature search identified all phase 3 RCTs of anticancer therapy for haematological cancers and solid tumours published globally during 2014-2017. Descriptive statistics, chi-square tests and the Kruskal-Wallis test were used to compare RCT design results, and output between haematological cancers and solid tumours as well as for different haematological cancer subtypes.

Results

694 RCTs were identified; 124 in haematological cancers and 570 in solid tumours. Overall survival (OS) was the primary endpoint in only 12% (15/124) of haematological cancer trials compared to 35% (200/570) in solid tumours (p < 0.001). Haematological cancer RCTs evaluated the systemic novel therapy more often than the solid tumour RCT (98% versus 84%, p = 0.002). Use of surrogate endpoints like progression-free survival (PFS) and time to treatment failure (TTF) were more common in haematological cancers than solid tumours (47% versus 31%, p < 0.001). Within haematological cancers, the use of PFS and TTF was more prevalent in chronic lymphocytic leukaemia and multiple myeloma as compared to others (80%-81% versus 0%-41%, p < 0.001). Seventy-eight percent of haematologic trials were funded by industry as compared to 70% of solid tumour trials. Only 4% (5/124) of haematologicalcancer trials were led by investigators in upper-middle and lower-middle-income countries as compared to the 9% of solid tumour trials.

Conclusion

The fact that only 12% of haematological cancer RCTs are designed to show improvements in OS is of grave concern for the field and the care of future patients. This is further compounded by the highly prevalent use of alternative primary endpoints that are rarely valid surrogates for OS in haematological cancers.

Revisiting the Role of Alkylating Agents in Multiple Myeloma: Up-to-Date Evidence and Future Perspectives

From the 1960s to the early 2000s, alkylating agents (e.g., melphalan, cyclophosphamide, and bendamustine) remained a key component of standard therapy for newly-diagnosed or relapsed/refractory multiple myeloma (MM). Later on, their associated toxicities (including second primary malignancies) and the unprecedented efficacy of novel therapies have led clinicians to increasingly consider alkylator-free approaches. Meanwhile, new alkylating agents (e.g., melflufen) and new applications of old alkylators (e.g., lymphodepletion before chimeric antigen receptor T-cell [CAR-T] therapy) have emerged in recent years. Given the expanding use of antigen-directed modalities (e.g., monoclonal antibodies, bispecific antibodies, and CAR-T therapy), this review explores the current and future role of alkylating agents in different treatment settings (e.g., induction, consolidation, stem cell mobilization, pre-transplant conditioning, salvage, bridging, and lymphodepleting chemotherapy) to ellucidate the role of alkylator-based regimens in modern-day MM management.

Peptide cargo administration: current state and applications

Effective delivery of drug molecules to the target site is a challenging task. In the last decade, several innovations in the drug delivery system (DDS) have tremendously improved the therapeutic efficacy of drug molecules. Among various DDS, cell-penetrating peptides (CPPs) based DDS have gathered notable attention owing to their safety, efficacy, selectivity, specificity, and ease of synthesis. CPPs are emerging as an efficient and effective pharmaceutical nanocarriers-based platforms for successful management of various important human health disorders. Failure of several current chemotherapeutic strategies is attributed to low solubility, reduced bioavailability, and off-target delivery of several anti-cancer drugs. Similarly, development of therapeutics for vision-threatening disorders is challenged by the anatomical as well as physiological complexity of the eye. Such therapeutic challenges in cancer and ocular disease management can be overcome by developing cell-penetrating peptide (CPP) based peptide drug conjugates (PDCs). CPPs can be used to deliver various types of cargo molecules including nucleic acids, small molecules, and peptides/proteinaceous agents. In this review, we have briefly introduced CPPs and the linker strategies employed for the development of PDCs. Furthermore, recent studies employing CPP-based PDCs for cancer and ocular disease management have been discussed in detail highlighting their significance over conventional DDS. Later sections of the review are focused on the current status of clinical trials and future implications of CPP-based PDCs in vaccine development. KEY POINTS: • Cell-penetrating peptides (CPPs) can deliver a variety of cargo macromolecules via covalent and non-covalent conjugation. • CPP-based peptide drug conjugates (PDCs) can overcome drawbacks of conventional drug delivery methods such as biocompatibility, solubility, stability, and specificity. • Various PDCs are in clinical trial phase for cancer and ocular therapeutics.

Management of Relapsed-Refractory Multiple Myeloma in the Era of Advanced Therapies: Evidence-Based Recommendations for Routine Clinical Practice

Multiple myeloma (MM) is the second most common hematologic malignancy in adults worldwide. Over the past few years, major therapeutic advances have improved progression-free and overall survival, as well as quality of life. Despite this recent progress, MM remains incurable in the vast majority of cases. Patients eventually relapse and become refractory to multiple drug classes, making long-term management challenging. In this review, we will focus on the treatment paradigm of relapsed/refractory MM (RRMM) in the era of advanced therapies emphasizing the available novel modalities that have recently been incorporated into routine practice, such as chimeric antigen receptor T-cell therapy, bispecific antibodies, and other promising approaches. We will also discuss major factors that influence the selection of appropriate drug combinations or cellular therapies, such as relapse characteristics, and other disease and patient related parameters. Our goal is to provide insight into the currently available and experimental therapies for RRMM in an effort to guide the therapeutic decision-making process.

Trial designs and endpoints for immune therapies in multiple myeloma

Immune therapies, including CAR-T cells, bispecific antibodies, and antibody-drug conjugates, are revolutionizing the treatment of multiple myeloma. In this review, we discuss clinical trial design considerations relevant to immune therapies. We first examine issues pertinent to specific populations, including elderly, patients with renal impairment, high-risk/extramedullary disease, and prior immune therapies. We then highlight trial designs to optimize the selection of dose and schedule, explore rational combination therapies based on preclinical data, and evaluate the nuances of commonly used endpoints. By exploiting their pharmacokinetic/pharmacodynamic profiles and utilizing novel translational insights, we can optimize the use of immune therapies in multiple myeloma.

More Than 2% of Circulating Tumor Plasma Cells Defines Plasma Cell Leukemia-Like Multiple Myeloma

PURPOSE

Primary plasma cell leukemia (PCL) is the most aggressive monoclonal gammopathy. It was formerly characterized by ≥ 20% circulating plasma cells (CTCs) until 2021, when this threshold was decreased to ≥ 5%. We hypothesized that primary PCL is not a separate clinical entity, but rather that it represents ultra-high-risk multiple myeloma (MM) characterized by elevated CTC levels.

METHODS

We assessed the levels of CTCs by multiparameter flow cytometry in 395 patients with newly diagnosed transplant-ineligible MM to establish a cutoff for CTCs that identifies the patients with ultra-high-risk PCL-like MM. We tested the cutoff on 185 transplant-eligible patients with MM and further validated on an independent cohort of 280 transplant-ineligible patients treated in the GEM-CLARIDEX trial. The largest published real-world cohort of patients with primary PCL was used for comparison of survival. Finally, we challenged the current 5% threshold for primary PCL diagnosis.

RESULTS

Newly diagnosed transplant-ineligible patients with MM with 2%-20% CTCs had significantly shorter progression-free survival (3.1 v 15.6 months; P < .001) and overall survival (14.6 v 33.6 months; P = .023) than patients with < 2%. The 2% cutoff proved to be applicable also in transplant-eligible patients with MM and was successfully validated on an independent cohort of patients from the GEM-CLARIDEX trial. Most importantly, patients with 2%-20% CTCs had comparable dismal outcomes with primary PCL. Moreover, after revealing a low mean difference between flow cytometric and morphologic evaluation of CTCs, we showed that patients with 2%-5% CTCs have similar outcomes as those with 5%-20% CTCs.

CONCLUSION

Our study uncovers that ≥ 2% CTCs is a biomarker of hidden primary PCL and supports the assessment of CTCs by flow cytometry during the diagnostic workup of MM.

Time-to-event surrogate end-points in multiple myeloma randomised trials from 2005 to 2019: A surrogacy analysis

Use of surrogate end-points such as progression-free survival (PFS) and other time-to-event (TTE) end-points is common in multiple myeloma (MM) clinical trials. This systematic review characterises all published randomised controlled trials (RCTs) in MM using PFS or other TTE end-points between 2005 and 2019 and assesses strength of surrogacy of PFS for overall survival (OS). The association between OS hazard ratios (HRs) and PFS HRs was evaluated with linear regression, and the coefficient of determination with Pearson's correlation. We identified 88 RCTs of which 67 (76%) used PFS as the primary/co-primary end-point. One trial indicated whether progression was biochemical or clinical. Of the variance in OS, 39% was due to variance in PFS. Correlation between PFS and OS was weak (0.62, 95% confidence interval [CI] 0.38-0.78). In newly diagnosed MM, 43% of the variance in OS was due to changes in PFS. The correlation between PFS and OS was weak (0.65, 95% CI 0.30-0.84). In relapsed/refractory MM, 58% of the variance in OS was due to changes in PFS. Correlation between PFS and OS was medium (0.76, 95% CI 0.42-0.91). We demonstrate that PFS and progression characteristics are characterised poorly in MM trials and that PFS is a poor surrogate for OS in MM.

Isatuximab Plus Carfilzomib and Dexamethasone Versus Carfilzomib and Dexamethasone in Patients with Relapsed Multiple Myeloma: IKEMA Subgroup Analysis by Prior Transplantation

In the era of highly active novel agents for multiple myeloma (MM), the role, ideal timing, and impact of transplantation on further therapy after relapse remains a matter of debate. The impact of prior transplantation on treatment benefit from monoclonal antibodies in patients with relapsed/refractory MM (RRMM) is largely unknown. Few Phase 3 studies of monoclonal antibody combinations with proteasome inhibitors or immunomodulatory agents have reported outcomes according to transplantation status. This subgroup analysis examined efficacy and safety in patients from the Phase 3 IKEMA study with and without previous transplantation. IKEMA (NCT03275285) was a randomized, open-label, multinational, parallel-group Phase 3 study that investigated isatuximab (Isa), an anti-CD38 monoclonal antibody, combined with carfilzomib and dexamethasone (Isa-Kd; experimental group) versus Kd (control group) in 302 patients with RRMM and 1 to 3 prior lines of therapy. Patients were randomized in a 3:2 ratio to either Isa-Kd or Kd, with stratification by number of prior lines (1 versus more than 1) and Revised International Staging System (R-ISS) stage (I or II versus III versus not classified). Treatment was given until progressive disease, unacceptable adverse events, or patient choice. Of the 302 randomized patients in IKEMA, 185 (61.3%) had received a prior transplant, comprising 116 of 179 (64.8%) patients in the Isa-Kd arm and 69 of 123 (56.1%) patients in the Kd arm. After a median follow-up of 20.6 months, median progression-free survival (PFS) in patients with prior transplant was not reached with Isa-Kd versus 19.15 months with Kd (hazard ratio [HR] = 0.60; 99% confidence interval [CI], 0.31-1.16). After a median follow-up of 20.8 months, median PFS in patients without prior transplant was not reached with Isa-Kd versus 18.99 months with Kd (HR = 0.44; 99% CI, 0.18-1.05). The overall response rate in patients with prior transplant was 87.9% (Isa-Kd) versus 85.5% (Kd). More patients in the Isa-Kd arm achieved a complete response or better compared with the Kd arm (43.1% versus 29.0%). The overall response rate in patients without prior transplant was 84.1% (Isa-Kd) versus 79.6% (Kd). More patients in the Isa-Kd arm achieved a complete response or better compared with the Kd arm (33.3% versus 25.9%). The minimal residual disease negativity rate was higher with Isa-Kd versus Kd in patients with (31.9% versus 13.0%) and without prior transplantation (25.4% versus 13.0%). In patients with prior transplant, Grade 3 or higher treatment-emergent adverse events (TEAEs) were more common with Isa-Kd; however, no increases in serious TEAEs or definitive treatment discontinuations were seen versus Kd. Among patients without prior transplant, serious treatment-related TEAEs were similar, and there were fewer TEAEs leading to definitive discontinuation with Isa-Kd. The most common Grade 3 or higher TEAEs in patients with and without prior transplant were hypertension and pneumonia. For patients who underwent prior transplantation, Isa-Kd is an effective treatment option. Overall, these data demonstrate that Isa-Kd represents a standard of care for patients with RRMM, regardless of prior transplant status.

Recent Advances in the Applications of Small Molecules in the Treatment of Multiple Myeloma

Therapy for multiple myeloma (MM), a hematologic neoplasm of plasma cells, has undergone remarkable changes over the past 25 years. Small molecules (molecular weight of less than one kDa), together with newer immunotherapies that include monoclonal antibodies, antibody-drug conjugates, and most recently, chimeric antigen receptor (CAR) T-cells, have combined to double the disease's five-year survival rate to over 50% during the past few decades. Despite these advances, the disease is still considered incurable, and its treatment continues to pose substantial challenges, since therapeutic refractoriness and patient relapse are exceedingly common. This review focuses on the current pipeline, along with the contemporary roles and future prospects for small molecules in MM therapy. While small molecules offer prospective benefits in terms of oral bioavailability, cellular penetration, simplicity of preparation, and improved cost-benefit considerations, they also pose problems of toxicity due to off-target effects. Highlighted in the discussion are recent developments in the applications of alkylating agents, immunomodulators, proteasome inhibitors, apoptosis inducers, kinesin spindle protein inhibitors, blockers of nuclear transport, and drugs that affect various kinases involved in intracellular signaling pathways. Molecular and cellular targets are described for each class of agents in relation to their roles as drivers of MM.

Treatment Horizon in Multiple Myeloma

OBJECTIVES

This paper reviews current and emerging therapies for MM.

METHODS

Narrative review RESULTS: Multiple myeloma (MM) is a complex, heterogenous condition, and in recent years there has been an expansion in the number and range of treatments. Several new treatment approaches, including enhanced monoclonal antibodies, antibody-drug conjugates (ADC), bispecific T-cell engagers (BiTE) and chimeric antigen-T-cell therapy (CAR-T) are under development.

CONCLUSIONS

The emergence of new treatments that aim to tackle MM-associated immune dysfunction has led to improvements in overall survival.

Melflufen for the treatment of multiple myeloma

INTRODUCTION

Melphalan flufenamide (melflufen) is a first-in-class peptide-drug conjugate that takes advantage of increased aminopeptidase activity inside tumor cells to rapidly release alkylating agents therein. Melflufen in combination with dexamethasone has been evaluated in multiple clinical trials in patients with relapsed/refractory multiple myeloma (MM).

AREAS COVERED

This profile covers the unique mechanism of action of melflufen, the preclinical results supporting its activity in cellular models of resistance to chemotherapy, its activity in animal models of MM, and the clinical pharmacokinetics of melflufen. Findings from clinical trials evaluating melflufen, including the pivotal phase II HORIZON study and the phase III OCEAN study, are discussed.

EXPERT OPINION

Although MM treatment has improved, patients with disease refractory to multiple standard-of-care drug classes face a dismal prognosis. Melflufen demonstrated efficacy and tolerability in select populations, with an initial approval in the United States in patients with ≥ four previous lines of therapy and triple-class-refractory MM. Results from the phase III OCEAN study - currently under discussion with regulatory agencies in the United States and Europe - are more complex and have been put into context herein. Lastly, melflufen provides a proof-of-concept for the utility of the peptide-drug conjugate platform in relapsed/refractory MM.

How I treat triple-class refractory multiple myeloma

Immunomodulatory imide drugs (IMiDs), proteasome inhibitors (PIs) and anti-CD38 monoclonal antibodies (MoAbs) are the pillars of modern multiple myeloma (MM) therapy. The prognosis of patients with MM that became refractory to these three classes (triple-class refractory [TCR]) is historically poor. Observational studies indicate an overall response rate of ~30% and overall survival inferior to 1 year with existing therapies. While no randomised trial has been completed in this setting, several agents exploring new mechanisms of action showed activity in TCR MM in single-arm trials, including anti-B-cell maturation antigen (BCMA) chimeric antigen receptor T cells, anti-BCMA antibody-drug conjugates and exportin 1 (XPO1) inhibitors. Among agents in development, anti-BCMA bispecific T-cell engagers (TCE), and non-BCMA TCEs demonstrated activity in most patients. Additionally, specific agents may exhibit unique activity in biologically defined patient subsets, as exemplified by venetoclax in t(11;14) MM. The main open questions in TCR MM are preferred sequence of existing therapies, the utility of sequential use of agents with similar mechanism of action, but different immunotherapy target and the relative efficacy of the different anti-BCMA platforms. Here, we summarise the existing literature and provide general guidance on selecting therapy for this challenging and heterogenous group of patients.

The approval and withdrawal of melphalan flufenamide (melflufen): Implications for the state of the FDA

•

Melflufen, a new compound derived from melphalan, was withdrawn from the US market after excess deaths in a phase three confirmatory trial.

•

This occurred after accelerated approval: for new compounds derived from known drugs, the accelerated pathway principles must be questioned.

•

Allowing a new compound on the market, while there are known alternatives, and imminent confirmatory data, has the potential to harm patients.

In October 2021, melphalan flufenamide (melflufen) was withdrawn from the US market for the treatment of multiple myeloma. The decision occurred based on results from a phase 3 randomized controlled trial (RCT) which showed numerically inferior overall survival, which previously led the FDA to halt all trials involving this drug. We highlight four issues raised by the approval fate of melflufen. First, the OCEAN trial was designed with a substandard control arm: negative results occurred despite this bias theoretically favoring the experimental arm. Second, a new compound, derived from a well-known drug, is not well fitting the accelerated pathway principles, unless being robustly tested against its parent drug. Third and four, allowing a new compound on the market, while there are known alternatives, and imminent confirmatory data, has the potential to harm patients while bringing earlier market share and profit to the company. While the FDA and the company should be commended for pushing a potentially dangerous product off the US market despite recent approval, yet a re-evaluation of regulatory processes is needed to ensure that cancer patients have timely access to effective medications while being protected against potentially detrimental ones.

The Role of Belantamab Mafodotin, Selinexor, and Melflufen in Multiple Myeloma

PURPOSE OF REVIEW

Multiple myeloma (MM) is a hematologic malignancy of plasma cells that remains incurable with currently available therapies including proteosome inhibitors, immunomodulators, monoclonal antibodies, corticosteroids, and alkylators, in addition to autologous stem cell transplantation in patients who are eligible. Novel therapeutics are therefore required to improve patient outcomes. The goal of this paper is to review the role of three new agents in the MM treatment landscape: belantamab mafodotin, selinexor, and melflufen.

RECENT FINDINGS

All three agents have demonstrated clinical activity in patients with MM. Belamaf is the first FDA-approved anti-BCMA targeted agent, showing single-agent response rates of 60% and higher response rates of 48-100% in combinations. The majority of patients treated with belamaf experience corneal toxicity which remains the main challenge with its use; however, fortunately, the vast majority of patients recover. Selinexor is also FDA approved for the treatment of relapsed MM, with single-agent response rates of 26% and combination rates of 48-65%. Gastrointestinal side effects are common with selinexor use, with roughly 65% of patients experiencing nausea, 50% anorexia, 35% vomiting, and 42% diarrhea, the majority of which are grades 1-2. Both agents have a plethora of ongoing clinical trials with data forthcoming on various combinations with standard backbone agents as well as additional novel treatments. While melflufen showed promising initial data showing single-agent response rates of about 30%, inferior survival outcomes in patients previously treated with ASCT in the phase 3 OCEAN study lead to early termination of the trial and subsequent removal from the US market. Belamaf, selinexor, and melflufen are active agents to treat myeloma. Belamaf and selinexor are current options for the treatment of relapsed multiple myeloma with improved response rates and durability when used in triplet combinations. The optimal timing of use and treatment combinations of both agents in the context of additional immunotherapeutics entering the MM landscape requires further study. Many prospective studies are in development and promise to afford further clarity in the near future.